Warm Running Device

[dpreston Virginia]

My 69 280SL has been running rich and quickly fouls the spark plugs. I have gone through the linkage tour, check cold start valve (working perfect), replaced injectors and now I removed the Warm Running Device. It was thoroughly stuck.
I have cleaned it and hit it with PB blaster, then grease I have finally gotten it to move by hand but not to allow it to move freely enough for the plunger to move it. Do I need to take it completely apart? If so how do I do that or how to I free it up?
Photos show the movement I can pushing the valve open and close.

Thanks for any help to fix my WRD.
David Preston

[rwmastel]

You're a Full Member, anything in the Tech Manual?

[dpreston Virginia]

Not how to take it apart and get it working.

[Pawel66]

I think taking it apart is, basically, unscrewing two screws and parts you get are shown here: https://www.sl113.org/wiki/Engine/WarmRunningDevice

How to get it working - I think it is about freeing the valve if it is stuck, making sure that the thermostat is working and then adjusting it with two types of shims. Technical Manual covers all if it in essence.

As for freeing up the valve:

https://www.sl113.org/forums/index.php?topic=14134.msg96068#msg96068

https://www.sl113.org/forums/index.php?topic=14271.msg97165#msg97165

As for checking if the thermostat is working, e.g. here:

https://www.sl113.org/forums/index.php?topic=30847.0

Use a pot or kettle, thermometer and measure extention of the thermostat pin

AS for adjusting:

Oval shims regulate fuel mixture during warm up - more shims, richer mixture.
Round shims regulate time when WRD is working (depends on temperature) - more shims means longer work of WRD.

Search on the forum will point to a lot more materials.

[Pinder]

I found this video to be a good explaination

https://www.youtube.com/watch?v=F6sxlOFmoYw

[dpreston Virginia]

What a great how to video! Thanks for sharing!

[Pinder]

To free up the mechanism reemove the air filter, (should screw off) and spray your favoirte WD40 or equivelant to free it up so it moves smoothly, sea foam etc spray it every hole.

[Pawel66]

Maybe also:
- during the kettle test, you can just blow through the device to see if the thermostat is closing the air

- when you are putting it back together, it is good to apply some sealant between thermostat and its housing; the sticking of the air valve comes often from coolant dripping down there where the valve is and leaves residue that makes the valve and plunger stuck

[dpreston Virginia]

Took the valve completely apart and lightly sanded the inside of the body and the valve. Then added some grease. Reinstalled and the car is running well.

Thanks for all the help especially Joe Alexander. What a great community.

[rwmastel]

dpreston,

That's great!  Good work.  I have two questions.

... lightly sanded the inside of the body and the valve.

Why?

Then added some grease.

Where?

[dpreston Virginia]

I sanded the air valve and air valve housing with 800 grit paper. And then put grease in the housing to ensure smooth easy movement.

David


Photo of these parts are in technical manual at: https://www.sl113.org/wiki/Engine/WarmRunningDevice

[rwmastel]

But, nothing moves in the hosing.  It's just a place for the thermostat to sit and be affected by water temperature.

[rwmastel]

Oh, you meant air valve housing.  Duh!  Sorry.